Muscular System Flashcards
Three principal kinds of movement
- ameboid
- ciliary and flagellar
- muscular
- where movement depends on
- can change their form to relax or contract
contractile proteins
most important contractile system
actomyosin system
- supply force for movement
- restrain motion
- act on the viscera to effect their activity
- muscle sphincters that control the passage of materials out of tubular ducts
- plays a role in heat production
muscular system
- composes the muscular system
- capable of contracting when stimulated by nerve impulses
muscle fibers
Major categories of muscle:
histology
- skeletal muscle
- cardiac muscle
- smooth muscle
- long, cylindrical, multinucleated muscle fibers, each with striations
- voluntary control
- usually associated with bones and cartilages
- contractions are rapid
- packed with myofibrils
skeletal muscle tissue
chain of repeating units
sarcomere
- occurs only in the heart
- contains myofibrils and filaments of actin and myosin
- cells are short, mononucleate, often branched and joint to each other by distinct intercalated discs into sheets involuntary and myogenic
cardiac muscle tissue
- lack striations and almost entirely concerned with visceral functions
- mononucleate, short and fusiform in shape
- involuntary, contraction are slow and sustained
- visceral organs except heart, vessels, tubes, ducts
smooth muscle tissue
Major categories of muscle:
role
- somatic muscles
- visceral muscles
- orient the body of the organism in the external environment
- striated muscles that are attached to the ligaments, tendons and bones
- derivatives of the myotomes of mesodermal somites
- innervated by spinal nerves
- voluntary
somatic muscles
- pharyngeal arches and its derivatives
- adductors, constrictors, and levators that operate the jaws and successive gill arches
branchiomeric somatic muscles
- maintain an appropriate internal milieu
- smooth muscles of hollow organs, vessels, tubes, and ducts, intrinsic musculature of the eyeball, erector
- muscles of feathers and hair
- includes cardiac muscle
- derived from splanchnic mesoderm
- innervated by the autonomic nervous system
visceral muscles
consists of skeletal muscle cells (which, in turn, consist of myofibrils and myofilaments)
Muscle
extensions of a muscle’s tough connective tissue sheath (fascia & epimysium) that anchor a muscle to its origin & insertion
Tendons
immediate source of energy
ATP
when is glucose broken down
aerobic metabolism
stores and supply glucose
glycogen
energy reserve of muscles
creatine phosphate
rely heavily on glucose and oxygen
slow and fast oxidative fibers
rely on anarobic glycolysis
fast glycolytic fibers
incur during anaerobic glycolysis
oxygen debt
Classification of skeletal muscle fiber
- oxidative or glycolytic fibers by ATP source
- fast-twitch or slow-twitch fibers by speed of muscle contraction
- for slow, sustained contractions without fatigue
- contain extensive blood supply
- high density of mitochondria
- abundant stored myoglobin (protein that binds oxygen more tightly than hemoglobin does)
- important in maintaining posture in terrestrial vertebrates
slow oxidative fibers (red muscles)
two kinds of fast fibers
- fast glycolytic fiber
- fast oxidative fiber
- lacks efficient blood supply
- pale in color
- function anaerobically
- fatigue rapidly
fast glycolytic fiber (white muscles)
- extensive blood supply
- high density of mitochondria and myoglobin
- function aerobically
- for rapid, sustained activities
fast oxidative fiber
importance of tendons in energy storage
KE is stored from step to step as elastin strain energy in tendons
Vertebrate muscles
- skeletal, striated, voluntary muscles
- non-skeletal, smooth, chiefly involuntary muscles
- cardiac muscles
- electric organs
skeletal, striated, voluntary muscles
- axial
- appendicular
- branchiomeric
- integumentary
homologous to the branchial/pharyngeal muscles from fishes to mammals, straited muscles, innervated by cranial nerves
branchiomeric
- site of attachment that is relatively fixed
- the bone on which it originates is not displaced when the muscle contracts
Origin
site of attachment that is normally displaced by contraction of the muscles
Insertion
free part, in between the origin and insertion
Belly
long, seamlike tendons in the midventral line of the trunk (linea alba)
Raphes
e.g. of raphes
linea alba
tough, thin, sheetlike expances of mammalian tendons and ligaments (galea aponeurotica)
Aponeuroses
e.g. of Aponeuroses
galea aponeurotocia
shape of biceps brachii
fusiform
shape of sternomastoid of mammals
straplike
type of skeletal muscle that has muscle fibers that attach to a central tendon at an oblique angle, similar to the shape of a feather
pinnate muscle
shape of diaphragm with a central tendon
domed shaped
straighten two segments of a limb or vertebral column at a joint
extensors
draw one segment toward another
flexors
displacement toward from the midline
adductors
displacement away from the midline
abductors
cause a part to thrust forward or outward
protractors
pull the part back
retractors
raise a part
levators
lower a part
depressors
rotation of a part on its axis
rotators
rotators that turn the palm upward
supinators
turn the palm downward
pronators
making a part more taut
tensors
compress internal parts
consrictors
constrictors that make an opening smaller
sphincters
make an opening bigger
dilators
same embryonic origin and nerve supply
homologies
- skeletal muscles of the trunk & tail
- hypobranchial muscles & muscles of the tongue
- extrinsic eyeball muscles
- metameric
- segmental because of their embryonic origin; arise from segmental mesodermal somites
axial muscle
separated by myosepta
myomeres
- serve as origins and insertion of segmented muscles
- separates myomeres
myosepta
divides myomeres into dorsal and ventral
horizontal septum
above the septum
epaxials
below the septum
hypaxials
separate the myomeres of the 2 sides of the body
middorsal and midventral septa (linea alba)
elongated bundles that extend through many body segments & that are located below the expanded appendicular muscles required to operate the limbs
epaxials
- of the abdomen have no myosepta & form broad sheets of muscle
- are oriented into oblique, rectus, & transverse bundles
hypaxials
longest bundles
- longissimus group
- spinalis group
- iliocostalis group
lies on transverse processes of vertebrae; includes the longest epaxial bundles
longissimus group
subdivisions of longissimus group
- longissimus dorsi
- longissimus cervicis
- longissimus capitis
- lies close to neural arches
- connects spinous processes or transverse processes with those several vertebrae anteriorly
spinalis group
- lateral to longissimus & spinalis
- arises on ilium & inserts on dorsal ends of ribs or uncinateprocesses
iliocostalis group
- shortest bundles
- remain segmented
- connect processes (spinous, transverse, & zygapophyses) of adjacent vertebrae
intervertebrals
side-to-side movements of vertebral column
short epaxials
arch & support the vertebral column
short & long bundles
attach to & move the skull
most anterior bundles
- myosepta & ribs restricted to the thorax
- hypaxials form 3 layers: external oblique, internal oblique, & transverse
modern amniotes
- weakly developed in most fish;
- ‘stronger’ in tetrapods
- support ventral body wall & aid in arching the back
- in mammals - rectus abdominis
Rectus muscles
- hypobranchials extend forward from pectoral girdle & insert on mandible, hyoid, and gill cartilages
- hypobranchials strengthen floor of pharynx and assist branchiomeric muscles in elevating floor of mouth, lowering jaw, and extending gill pouches
Fish
- hypobranchials stabilize and move hyoid apparatusand larynx
- the tongue of amniotes is a ‘sac’ anchored to hyoid skeleton & filled with hypobranchial muscle
Tetrapods
- consists of a number of electric disc piles in either vertical or horizontal columns
- each disc (electroplax) is a large coin-shaped cells
- functions: defense, communication, locating prey (electrolocation)
Electric organs